The sera of 33 workers in an Egyptian asbestos cement pipe factory have been examined for immunoelectrophoretic pattern changes. A decrease in the prealbumin and albumin fractions was found, with an increase in the α1 glycoprotein, α2 lipoprotein, transferrin IgG, IgM and IgA fractions. No correlation was found between these changes and the period of exposure or the degree of asbestosis.